This invention relates to equipment for manufacturing packages, and more particularly, to apparatus and methods for rotating a flat packaging article presented in a first orientation through a predefined angular displacement to release the article in a second orientation.
A variety of products are transported and distributed in sacks or bags constructed of paper or another strong, but flexible, planar material. Relatively large bags are often required as packaging for pet foods, food stocks, seed, fertilizer, and other products, in quantities from around 10 to 150 pounds. A typical bag constructed for use in such applications comprises an elongate, substantially tubular body section having a top end and a bottom end. A closure is generally provided at each of the top and bottom ends so that product to be contained in the bag does not leak out. Several processes are available for manufacturing such bags.
A bag construction method preferred in the industry is to form the planar material into a flattened "tube" section in a first manufacturing step. At the end of this step, the sides of the bag are complete, but the top and bottom ends are left open. In a subsequent manufacturing step, at least one of the top or bottom ends are closed by sewing, gluing, or another appropriate closure method.
Typical automated manufacturing equipment for performing the first manufacturing step emits the partially completed bags or "tubes" in an end-first orientation. Further, such equipment is typically elongate in shape, and upon exit from the machine, the tube travels in a direction approximately aligned with the longitudinal axis of the machine.
Typical equipment for performing the second manufacturing step (i.e. securely closing at least one end of the tube) requires that the tubes to be processed be presented in a side-first orientation--that is, an orientation approximately perpendicular to the orientation in which they are emitted by the equipment of the first manufacturing step.
For example, in some closure equipment, the component which applies the closure remains stationary, and one of the open ends of the tube is moved across it in a straight-line fashion parallel to the open edge. As a result of the relative motion between the tube and the closure component, the closure component effectively traces a linear path adjacent and parallel to the open end of the tube. Since the path of tube travel is generally aligned with the longitudinal axis of the machine, this configuration requires that the open end of the tube also be aligned along the longitudinal axis of the machine, and the tube must be presented in a side-first orientation to the closure equipment.
Because the second manufacturing step requires the tube in an orientation different than that produced in the first manufacturing step, it has heretofore been difficult to efficiently transfer the tubes at high speed from one process to the next. Tubes may be transferred in single units in a manual operation which includes rotating each tube through the necessary angular displacement. However, such manual transfers are labor-intensive and significantly limit the speed at which tubes may be processed. One proposed solution to this problem is to allow the output of the first process to accumulate in a stacking station, and then to manually transfer the tubes, en masse, to an unstacking station at the input of the second process. This method is also labor intensive, and has the additional disadvantage of requiring complex and expensive equipment to stack and unstack the tubes.
Another possible solution to this problem is to arrange the manufacturing machinery of the first and second processes at right angles (or another suitable angular displacement) with respect to one another, thereby avoiding the need to rotate the tubes. In such an arrangement, tubes produced in the first manufacturing step would automatically be properly oriented for further processing in the second manufacturing step. However, this solution also has several disadvantages. Many existing manufacturing facilities are constructed to accommodate substantially linear arrangements of machinery. Therefore, it may not be convenient to arrange two large manufacturing machines at right angles.
Also, in such an arrangement, although the orientation of the tubes produced in the first manufacturing step is compatible with that required in the second manufacturing step, the tube travel directions are not compatible. Accordingly, tubes which are emitted by the first process, and which may be moving rapidly in a first direction, must first be abruptly stopped and then accelerated in a second direction. Machinery to accomplish these functions is also complex and expensive. In addition, such machinery cannot operate quickly enough to accommodate the maximum operating speeds of other processing equipment. Thus, transfer of tubes between manufacturing steps has become a rate limiting step in the production of completed bags.
A variety of devices have been developed in the past for automatically rotating a tube or other article from a first orientation into a second orientation, through a desired angular displacement.
Auerbach U.S. Pat. No. 4,928,807 discloses an apparatus for turning flat articles such as envelopes. A pair of belts transport the envelope along a deck to a turning position. A rotatable and vertically reciprocable disk member is provided below an aperture in the deck at the turning position. A spring-biased pivot ball is provided above the aperture. When the envelope arrives at the turning position, cams displace the disk member upward through the deck aperture to pin the envelope against the pivot ball at the approximate center of gravity of the envelope. The disk is then rotated by 90 degrees under cam control. The envelope rotates with the disk. Once rotation is complete, the deck pivots upward, and belts and rollers associated therewith engage the envelope to transport it to an exit. DeBarber U.S. Pat. No. 5,207,858 appears to disclose a similar device.
These apparatus require that the article be rapidly accelerated and decelerated, both linearly and angularly. Accordingly, these devices are not suitable for use with articles substantially larger and heavier than an envelope. Applying the Auerbach/DeBarber apparatus to larger, heavier articles would not be feasible, because equipment to accomplish the large accelerations and decelerations required would be costly and complex. In addition, subjecting larger, heavier articles to such accelerations and decelerations may stress the articles and possibly damage them.
Achelpohl U.S. Pat. No. 4,372,436 discloses a tube rotating device employing rotating turntables. A tube forming machine and a base forming machine are adjacently spaced so that tubes being processed therethrough move in parallel but opposite directions. The Achelpohl device employs two rotating turntables and three linear conveyers which cooperate to receive a tube from the tube forming machine, change its direction of movement by 180 degrees, rotate the tube by 270 degrees, and supply it to the base forming machine.
Wojtowics U.S. Pat. No. 3,779,546 discloses another turntable-type device for changing the direction of a document. A rotating wheel has at least one platen for receiving and carrying a document. The platen employs vacuum inlets and a resilient surface to secure the document.
Stemmler U.S. Pat. No. 4,648,503 discloses an article turning device having a pair of closely spaced turntables, each rotating in the same direction and having intersecting article transport paths. Each turntable has a vacuum suction device to retain the article.
Like the devices disclosed by Auerbach and DeBarber, the devices of Achelpohl, Wojtowics, and Stemmler rely on rapid acceleration and deceleration of the article, and therefore suffer from many of the same disadvantages of cost and complexity. In addition, although the Achelpohl device may accommodate large articles, it does not operate quickly enough to match the speed of modern bag production equipment. In addition, Achelpohl does not accommodate an end-to-end arrangement of equipment for performing the first and second manufacturing steps.
Rochla U.S. Pat. No. 3,587,824 discloses an article for turning flat workpieces as they advance. A deck is provided which extends longitudinally in the direction of workpiece travel. The deck has a longitudinal opening along its length. Upper and lower conveyers are provided to synchronously convey a plurality of turning devices. Each conveyer includes a spaced pair of continuous chain loops with end sprockets. Each turning device includes a turntable mounted on a carriage assembly; each carriage appears to be attached to the chains at a single location. The upper and lower conveyers move synchronously so that the turntables cooperatively engage workpieces at one end of the deck and transport them to the other end. A cam controls the position of the turntable with respect to the carriage to avoid interference between the edge of a turntable and the workpiece or opposing turntable. The turning devices of at least one of the conveyers are cam driven to cause rotation of the workpiece. Von Hein U.S. Pat. No. 4,565,359 appears to disclose a device having many similarities to that of Rochla.
The Rochla and Von Hein devices are difficult to construct due to the complexity of synchronizing upper and lower conveyers. In addition, the Rochla device requires a complicated mechanism for controlling the vertical positions of the turntables as they approach the workpiece and table.